JP2013231728A - Micro-mechanical part incorporated into timepiece mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent attraction and adhesion of a moving micro-mechanical part to an adjacent part.SOLUTION: On all or a part of the surface of a micro-mechanical part made of insulating material, such as silicon and compound thereof, diamond, glass, ceramic, or other materials, a thin deposition of a layer of conductive material is conducted, such as non-oxidising and non-magnetic metal, and such as gold, platinum, rhodium or silicon. It makes it possible to remove the risk of attraction and adhesion with respect to an adjacent part.

Description

  The present invention relates to a micromechanical part made of an insulating material, and more particularly, to a clockwork fixed or movable part, in which particles are directly or indirectly caused by the proximity of the fixed or movable part to another part. The function of the moving parts is not hindered by attracting.

  Insulating materials of silicon and its compounds, quartz, diamond, glass, ceramic or other materials are used not only for fixed parts such as plates or receivers, but also for adjustment systems such as hairsprings, balances or escapements, Or, for the moving parts that form part of the mechanism, the watchmakers are more frequently used to make micromechanical parts.

  It has been observed that the use of silicon has one drawback, particularly with respect to a hairspring that is completely insulated from other components, for example by being held in a beard or bonded by a non-conductive adhesive. Certainly, after a certain operating time, some coils located between the outer end curve and the inner end curve of the hairspring tend to stick to the balance, which makes the adjustment system isochronous. Inevitably harmful. The same phenomenon can be observed for other parts made of silicon or other insulating material, which also ultimately has a detrimental effect on isochronism.

  Accordingly, it is an object of the present invention to provide a solution to the aforementioned problem by providing a fixed or movable micromechanical part made of an insulating material that avoids the risk of adhesion due to surface treatment.

  Therefore, the present invention relates to silicon and its compounds, diamond, glass, ceramic or other materials, all or part of which is coated with a thin deposit of conductive material, such as metallic or non-metallic conductive material. The present invention relates to a micro mechanical part made of such an insulating material. Preferably the conductive deposit has a thickness of less than 50 nm. This very thin deposit that is not visible to the naked eye but is perceptible by means of current analysis removes the risk of attraction by adjacent parts (this attraction is due to friction or tension that tends to create an electrostatic charge in the part) and adhesion.

  This deposition can be carried out on a monolithic cast or composite part of insulating material, ie at least the outer surface being made of insulating material.

  Of the materials capable of achieving the aforementioned objectives, non-oxidizing and non-magnetic metals such as gold, platinum, rhodium, palladium are preferably selected.

  Of the non-metallic conductive materials, graphite, carbon, doped silicon, and conductive polymer are preferably selected.

  These metals can be deposited by known methods that allow for thickness control by adjusting the operating conditions, for example by sputtering, PVD, doping, ion implantation or electrolysis. The same technique could be used to deposit non-conductive metallic materials.

In a preferred application, the micromechanical part is a part in a clockwork mechanism such as a hairspring, pallet, escape wheel or gear, or other fixed part capable of forming an arbor bearing of a movable part. is there. In the following detailed description, the present invention is particularly illustrated by the hairspring, which is the most sensitive part of a clockwork.
The invention also relates to a timepiece incorporating a micromechanical part of this type.

Fig. 3 shows a partially peeled plan view of a spring balance provided with a hairspring treated according to the invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 with a schematic illustration of the portion that has been peeled away.

  Other features and advantages of the present invention will appear more clearly in the following description of embodiments given by way of non-limiting description with reference to the accompanying drawings.

  The present invention is a hairspring 1 made of, for example, silicon from a plate of silicon or other amorphous or crystalline insulating material, applying micromachining techniques used in the manufacture of integrated circuits or accelerometers The spring balance adjusting apparatus shown in FIG. 1 will be described. For example, wet etching, dry plasma processing, or reactive ion etching (RIE) can be performed using a mask suitable for the contour desired for the hairspring.

  Given the small area, a group of hairsprings can be manufactured from the same silicon plate, the shape of which is determined by the thickness of the plate and the shape of the mask, said shape being for a hairspring that operates in one plane. Is calculated.

  Referring now to FIG. 2 where the cross-section is limited to the hairspring 1 and balance 9, the behavior of the coil 11 after a certain operating time is shown in the left part when the coil 11 has not undergone any treatment. It is. As can be seen, the coil 11 moves away from its normal position, indicated by the dotted line, and is attracted by the balance 9 and can also adhere to the balance 9, which is normal, i.e. in one plane. Interfering with the only stretching / contraction movement.

  The right part shows the hairspring 1 after processing, and the dotted line represents the position that the coil 11 will occupy when there is no processing. As can be seen, the hairspring remains completely in one plane. In fact, surprisingly, by carrying out a process consisting of a very thin deposition of a conductive material, such as a metallic material, on all or part of the coil surface, the inherent mechanical properties of the hairspring are thereby reduced. Without change, it was observed that the aforementioned detrimental effects disappeared. “Very thin deposition” means a deposition having a thickness of less than 50 nm, preferably 10-20 nm. When the deposit is less than 50 nm, the inherent mechanical properties of the part are not changed and the deposit is not visible to the naked eye but is nevertheless perceivable by current analysis techniques. When a conductive metal material is used, the material used is preferably a non-oxidizing and non-magnetic metal such as gold, platinum, rhodium, palladium. This deposition can be performed by various known methods such as sputtering, PVD, ion implantation or electrolytic deposition.

  As an example, a 15 nm gold deposition was performed by sputtering by applying a 60 mA current for 15 seconds.

  When the non-metallic conductive material is deposited, it is preferably selected from the group consisting of graphite, carbon, doped silicon, conductive polymers, and the aforementioned deposition techniques and thicknesses are used.

  We have described a silicon hairspring so far, but other amorphous or crystalline non-conductive materials as described above can also be used and treated by surface metallization to avoid the risk of attraction and adhesion it can.

  It is also possible to use a composite material to make a silicon core and, for example, a hairspring with a thick silicon dioxide coating from which a thin deposit of conductive material is made.

  The “composite material” may include a metal core embedded in an insulating material.

  Similarly, the present invention is not limited to a hairspring, but can be applied to other moving parts such as pallets, escape wheels or gears, and other fixed or moving parts of a clockwork.

1 Hairspring 9 Balance holder 11 Coil

Claims (7)

A micromechanical part made of at least one insulating material and incorporated into a clockwork mechanism,
The at least one insulating material is
A micromechanical component characterized in that all or part of the surface is coated with a coating layer formed by metal deposition .   2. Micromechanical component according to claim 1, characterized in that the metal deposit has a thickness of less than 50 nm, preferably 10-20 nm.   The micromechanical component according to claim 1, wherein the insulating material is selected from silicon and a silicon compound, diamond, glass, and ceramic.   4. The micromechanical component of claim 3, wherein the silicon dioxide coating comprises a silicon core formed thereon with a thickness greater than 50 nm.   The micromechanical component according to any one of claims 1 to 4, wherein the metal used to perform the deposition is a non-oxidizing material or a non-magnetic material.   The micromechanical component according to claim 5, wherein the metal is selected from gold, platinum, rhodium, and palladium.   7. A balance spring, a pallet, a escape wheel, an escapement such as a gear, or a component part of a spring balance system, or another fixed or moving part. Micro machine parts.

Images